Abstract: Low-side driver circuit (200) for data transmission applications includes external connection (202) for connecting and providing drive current to an external physical interface circuit. Sink transistor (210) forms an isolation from the physical interface circuit, and channels low-side drive current to external connection (202). Sink transistor (210) includes base (216), collector (208), and emitter (224). Emitter follower transistor (228) associates with sink transistor (210), and in conjunction with "A" input to the gate of transistor (228), sink transistor (210) controls the state of emitter follower transistor (228). Blocking transistor (206) associates with base (216) of sink transistor (210) to block the base of sink transistor (210) in the off state of sink transistor (210). Pull-down diodes (218) and (220) associate with base (216) of sink transistor (210) to pull down the voltage of the base when sink transistor (210) is in an off state.

Abstract: High-side physical interface driver circuit (10), for use in a variety of data transmission applications, includes an external connection (18) for connecting and providing drive current to an external physical interface. Output transistor (16) for channeling high-side drive current to external connection (18). Output transistor (16) includes base (18), collector (14), and emitter (24). Control transistor (28) controls the on state of output transistor (16) to supply high-side drive current to external connection (18). At least one shorting transistor (30) shorts base (19) of output transistor (16) to emitter (24), when high-side voltage reaches a predetermined minimum voltage level.